I dont know what GRIM says but I think it looks better for a altar server placing the Bl. Sacrament back in the tabernacle then the EM
I disagree. Typcally, altar servers aren’t even confirmed yet. The fact that altar servers usually wear albs and adult laypeople assisting at the altar typically don’t doesn’t change that. It might “look better”, but IMHO it isn’t at all preferable, if you think about it.
I’m not saying that it is forbidden for altar servers to do this if they are asked but that when the Blessed Sacrament needs to be moved, clergy are preferred over confirmed laypersons and that clergy would do better to ask an adult who is confirmed over someone who is not, even if it is becaues the young person is not old enough to have been confirmed.
Having said that, consider the story of St. Tarcisius, the patron of altar servers:
from:
ewtn.com/library/mary/tarcis.htm
*Tarcisius was a twelve-year-old acolyte during one of the fierce Roman persecutions of the third century, probably during that of Valerian. Each day, from a secret meeting place in the catacombs where Christians gathered for Mass, a deacon would be sent to the prisons to carry the Eucharist to those Christians condemned to die. At one point, there was no deacon to send and so St. Tarcisius, an acolyte, was sent carrying the “Holy Mysteries” to those in prison.
On the way, he was stopped by boys his own age who were not Christians but knew him as a playmate and lover of games. He was asked to join their games, but this time he refused and the crowd of boys noticed that he was carrying something. Somehow, he was also recognized as a Christian, and the small gang of boys, anxious to view the Christian “Mysteries,” became a mob and turned upon Tarcisius with fury. He went down under the blows, and it is believed that a fellow Christian drove off the mob and rescued the young acolyte.
The mangled body of Tarcisius was carried back to the catacombs, but the boy died on the way from his injuries…Pope St. Damasus wrote a poem about this “boy-martyr of the Eucharist” and says that, like another St. Stephen, he suffered a violent death at the hands of a mob rather than give up the Sacred Body to “raging dogs.”*
A boy can obviously be worthy of the serious responsibility of carrying the Blessed Sacrament.